Coated paper for printing

ABSTRACT

A coated paper for printing comprising a base paper and a coating layer containing a pigment and an adhesive, wherein the coating layer has a volume distribution of 65% or more of pigment particles ranging from 0.4 μm to 4.2 μm in size, and wherein the coated paper has a basis weight of 50 g/m 2  or less and tensile strength ranging between 200 kN/m and 400 kN/m, inclusive.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a coated paper for printing that islight in weight yet offers particularly excellent appearance in theunprinted state along with equally excellent printability.

[0003] 2. Description of the Related Art

[0004] There has been a strong demand of late for high-quality, coatedpapers for printing suitable for printed matter containing manyphotographs, illustrations and colors, given the desire to convey theprinted content with strong visual impact. On the other hand, there isalso a strong demand to reduce the weight of printed matter as a meansof saving energy and the costs of shipping and mailing. These two basicdemands are mutually exclusive, however, since high-quality, coatedpapers for printing use a heavier base paper and more coating materialand are more expensive, thus failing to meet the need for light weightand low cost. This has given rise to a need for technology that achieveshigher printing quality using a so-called “low-grade” coated paperhaving low basis weight and coating weight.

[0005] Whiteness, opacity, sheet gloss, printed gloss and stiffness areparticularly important among the qualities required of a coated paper.Whiteness enhances contrast, while opacity prevents the content on theback face of the printed page from showing through. Gloss affects thequality feel of the printed matter. It is essential that all theseproperties be satisfied while maintaining an optimal balance. Stiffnessmainly affects printing efficiency and is an important factor thatdetermines the ease with which the printed pages can be turned.

[0006] Coated papers are largely classified into glossy coated papersand matte-coated papers. Glossy coated papers include art papers andhigh-grade art papers used in the printing of expensive publications,and other coated papers used for printing catalogues, magazines,brochures, and so on. These papers, with their glossy finish, offerexcellent gloss in both the unprinted and printed areas of the finishedproduct. Matte-coated papers include those of dull finish and mattefinish and offer lower gloss in both unprinted and printed areas. Mattefinish makes the printed product look flat and heavy due to its lowgloss. Dull finish has a property intermediate between glossy and mattefinish, as it offers low sheet gloss but high printed gloss.

[0007] As mentioned above, reducing the weight of a coated paper forprinting requires a reduction in the basis weight of the base paper anda reduction in the weight of the coating layer. However, simply reducingthe basis weight without changing the composition of the paper materialwill reduce the paper thickness in proportion to the decrease in theweight of the paper, resulting in insufficient opacity and stiffness.Providing a thick coating layer on a base paper of low basis weight willretain the same level of printability achieved with a base paper ofnormal basis weight, but this approach is not practical because theopacity and stiffness will drop. Additionally, such a measure willreduce the tensile strength, possibly leading to problems during offsetweb printing such as torn paper on the turning cylinder, at the paster,or when the press is started.

[0008] Providing a coating layer with low coating weight on a base paperof high basis weight achieves sufficient opacity and stiffness. However,reducing the basis weight of a coated paper through this method willrequire a substantial reduction in the coating weight, in fact to adegree below what is necessary. That results in insufficient printingquality, so therefore the approach is impractical. In other words, acertain balance must be maintained between basis weight and coatingweight, requiring a combination of low-basis-weight base paper with acoating layer with low coating weight, or a high-basis-weight base paperwith a coating layer with high coating weight. Generally, papers withlower basis weight offer lower whiteness, opacity, sheet gloss, printedgloss and stiffness compared with those of higher basis weight.

[0009] Generally speaking, opacity drops dramatically when the basisweight becomes 80 g/m² or less. To minimize the drop in stiffness andopacity while reducing the basis weight to a certain extent, alower-density, higher-bulk paper should be produced. Such paper can bemade effectively using mechanical pulp from certain types of trees suchas gumwood, maple and birch. However, limiting the types of usable treesis not practical from the viewpoints of energy and economy. At any ratethe use of mechanical pulp, regardless of the source trees, helpsincrease stiffness and opacity. Methods known to reduce basis weight andimprove opacity include the addition of hollow synthetic resin capsules(Japanese Patent Publication No. 52-118116), and the addition of asynthetic organic foaming filler (such as EXPANSEL by Nippon Filant) andcausing the filler to foam in the drying stage. However, hollowsynthetic resin capsules and foaming fillers require a complex processof adjusting the mixing and foaming conditions, and they are alsoexpensive. Therefore, these are not presently seen as practical methods.Instead of using a filler, Japanese Patent Application Laid-open No.8-13380 proposes a method to add micro-fibril cellulose. However, thismethod is also impractical, because it requires that micro-fibrilcellulose be prepared separately, thus complicating the operation. It isknown that the addition of fillers, particularly titanium dioxide, tothe base paper increases opacity. However, it increases density whilereducing stiffness and paper strength. These factors prevent us fromsimply adding fillers.

[0010] As explained above, the simple application of the prior art willnot provide a lightweight coated paper for printing that possesses thedesired characteristics.

SUMMARY OF THE INVENTION

[0011] Given the aforementioned situation, the present invention aims toprovide a coated paper for printing that is light in weight yet offersopacity suitable for actual use, possessing a relatively goodink-impression property and high printed gloss, and particularly anexcellent printability that prevents the paper from tearing duringoffset web printing.

[0012] The inventors have carried out extensive studies to find ways tosolve the above problems, and have found that a coated paper forprinting consisting of a base paper and a coating layer containingpigment and adhesive will be light in weight yet offer opacity suitablefor actual use, possessing a relatively good ink-impression property andhigh printed gloss, and particularly an excellent printability thatprevents the paper from tearing during offset web printing, if saidcoating layer has a volume distribution of 65% or more of pigmentparticles ranging from 0.4 μm to 4.2 μm in size, and also if said coatedpaper has a basis weight of 50 g/m² or less and tensile strength between200 kN/m and 400 kN/m, inclusive. Such paper would therefore solve theabove problems. This finding has led to the invention presented here.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0013] In the present invention it is important to use a pigment whoseparticle size is between 0.4 μm and 4.2 μm for at least 65% of the totalpigment volume. The percentage of pigment particles ranging between 0.4μm and 4.2 μm is preferably from 65% to 90%.

[0014] If a pigment is used that contains many particles of smallerdiameter and where the percentage of pigment particles ranging between0.4 μm and 4.2 μm is less than 65% of the total pigment volume, sheetgloss will increase but printed gloss and coatability of the base paperwill decease relative to the use of a pigment containing many particlesof larger diameter. Therefore, if a pigment containing many particles ofsmaller diameter is used to reduce the coating weight, it is difficultto produce a coated paper for printing offering excellent appearance inthe unprinted state along with equally excellent printability, eventhough the basis weight of the base paper is increased. Further, if apigment is used that contains many particles of larger diameter andwhere the percentage of pigment particles between 0.4 μm and 4.2 μm isless than 65% of the total pigment volume, the printed gloss andcoatability of the base paper will improve but sheet gloss will becomeinsufficient by comparison to the use of a pigment containing manyparticles of smaller diameter. These facts still point to the difficultyof producing a coated paper for printing that offers excellentappearance in the unprinted state along with equally excellentprintability.

[0015] Any type of pigment can be used in the present invention, as longas the aforementioned volume-distribution range is satisfied. Theavailable pigments include those traditionally used in the production ofcoated papers, such as kaoline, clay, delaminated clay, ground calciumcarbonate, precipitated calcium carbonate, talc, titanium dioxide,barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicate,colloidal silica, satin white and other inorganic pigments. Thesepigments can be used alone or in any of various combinations. In thepresent invention it is preferable to use a combination of multiplepigments to achieve the desired properties such as the coatability andquality of the coated paper. However, in this case it is important thatthe particle size distribution of the overall pigment have at least 65%of all pigment particles in a range of 0.4 μm to 4.2 μm. The pigments tobe used in the present invention are required to have a certaincharacteristic in their particle size distribution; namely, they musthave particles of relatively larger size than those in normal coatingpigments, thereby accounting for a larger percentage of the overallpigment. Pigments that already have a desired particle size distributionmay be selected, or a pigment mixture with the specified particle sizerange may be created via classification. This way, the coatability ofthe base paper's surface can be increased even at a low coating weight,thereby achieving a relatively high degree of printed gloss.

[0016] In particular, it is preferable that 60 weight parts or more ofkaolin having the particle size distribution of 65% or more in a rangeof 0.4 μm to 4.2 μm, is used relative to 100 weight parts of pigment.

[0017] The present invention improves the sheet gloss and otherproperties of a coated paper for printing, provided that said papercontains between 1 and 20 weight-parts, inclusive, (preferably from 3 to15 weight-parts), of hollow plastic pigment with a diameter of 0.8 μm ormore (preferably from 0.8 μm to 1.5 μm) relative to 100 weight-parts ofpigment. Hollow plastic pigment with a particle diameter of less than0.8 μm will not achieve good coatability at low coating weight.Moreover, the bulk of the coating layer does not increase and sufficientopacity cannot be obtained.

[0018] The present invention also relates to a coated paper with a basisweight of 50 g/m² or less, preferably 48 g/m² or less, or better yet 45g/m² or less. If the basis weight of the coated paper is over 50 g/m²,the sufficient basis weight and coating weight of the base paper willachieve a level of opacity required in actual use. Further, there won'tbe a problem regarding ink-impression property, printed gloss or otherprintability characteristics. In the present invention, however, it ispreferable that between 0.5 and 12 wt-%, inclusive, (preferably from 1to 9 wt-%), of titanium dioxide be added to the coated paper to obtainsufficient opacity even at a low basis weight of 50 g/m² or less.Titanium dioxide can be added to the base paper, coating layer, or both.

[0019] Additionally, in the present invention it is important to set thetensile strength of the paper thus obtained to a level ranging from 200kN/m to 400 kN/m, inclusive, (preferably from 300 kN/m to 400 kN/m), asmeasured on a tensile tester by Lorentzen and Wettre, in order toprevent the paper from tearing during offset web printing. If thetensile strength exceeds 400 kN/m, a coated paper with a basis weight of50 g/m² or less cannot absorb all the tension applied to the paperduring offset web printing, and as a result it will tear easily. On theother hand, a tensile strength below 200 kN/m causes the coated paper tostretch easily, which makes positioning difficult during multicolorprinting on an offset web press. Tensile strength can be adjusted bychanging the conditions for making the base paper such as the J/W ratio,the content of added filler and dewatering level, the coating weight,and other conditions as necessary.

[0020] The various pulp materials that can be used to make thebase-paper mixture of the present invention include chemical pulp(bleached or unbleached kraft pulp from softwood, bleached or unbleachedkraft pulp from hardwood, etc.), mechanical pulp (groundwood pulp,thermomechanical pulp, chemi-thermomechanical pulp, etc.) and deinking(recycled) pulp, which may be used alone or in combination at arbitraryblending ratios. In the present invention the content of mechanical pulpshould ideally be 20% or more to improve opacity. The types of fillersthat may be added to the base paper include hydrated silicic acid, whitecarbon, talc, kaoline, clay, calcium carbonate, synthetic resin fillersand other known fillers. Besides the aforementioned pulps and fillers,aluminum sulfate, sizing agent, paper strength enhancer,retention-aiding agent, coloring agent, dye, defoaming agent and so onmay be added as necessary. The content of fillers is preferably from 3to 15 wt-%, more preferably from 6 to 12 wt-%, per total weight of thebase paper.

[0021] The adhesives that may be used in the present invention includethose traditionally used in the production of coated papers. Theyinclude various copolymers such as styrene-butadiene, styrene-acryl,ethylene-vinyl acetate, butadiene-methyl methacrylate and vinylacetate-butyl acrylate; synthetic adhesives such as polyvinyl alcohol,maleic anhydride copolymer and acrylate-methyl methacrylate copolymer;proteins such as casein, soybean protein and synthetic protein; starchessuch as oxidized starch, cationic starch, urea phosphate esterifiedstarch, hydroxyethyl etherified starch or other etherified starch, anddextrin; and cellulose derivatives such as carboxymethyl cellulose,hydroxymethyl cellulose and hydroxyethyl cellulose. One or more types ofnormal adhesives used for coated paper will be selected and used. Theseadhesives should be added roughly between 5 and 50 weight-parts, orbetter yet between 10 and 30 weight-parts, per 100 weight-parts ofpigment.

[0022] The coating mixture used in the present invention may containdispersant, thickener, water-retention agent, defoaming agent,waterproofing agent and various other additives regularly mixed into thecoating materials.

[0023] The base paper used in the present invention may be made in anarbitrary manner on a Fourdrinier paper machine equipped with top wire,etc., a cylinder paper machine, a board machine combining theaforementioned two, a Yankee dryer machine, and so on, using the acid,neutral or alkali paper method. The base paper thus obtained may also bepre-coated with starch, polyvinyl alcohol or other material using a sizepress, bill blade, gate-roll coater or premetering sizing press, or itcan be pre-coated with one or more layers of coating mixture containingpigment and adhesive.

[0024] The prepared coating mixture is applied to both sides of the basepaper, either one side at a time or simultaneously on two sides, in one,two or more layers using a blade coater, bar coater, roll coater,air-knife coater, reverse roll coater, curtain coater, size-presscoater, gate-roll coater, and so on. The ideal coating weight is between2 and 15 g/m², or better yet 3 and 10 g/m², per side of the base paper.

[0025] The wet coating layer may be dried in a steam-heated cylinder,hot-air heater/dryer, gas heater/dryer, electric heater/dryer, infraredheater/dryer or high-frequency heater/dryer, which may be used alone orin combination.

[0026] The coated and dried paper is then smoothed in a process notusing calendering, or it is treated through a process such assuper-calendering or high-humidity soft-nip calendering.

[EXAMPLES]

[0027] The following is a detailed explanation of the present inventionusing examples. Of course, the invention is not limited to the examplesprovided. Unless otherwise specified, “part(s)” and “%” in the examplesindicate weight-part(s) and wt-%, respectively. The coated papersobtained in the examples were tested through the following evaluationmethod:

[0028] <Evaluation Method>

[0029] Particle size distribution: Particle size distribution wasmeasured using a laser-diffraction type of particle-size measuringsystem by Malvern Instruments.

[0030] Sheet gloss: Measured in accordance with JIS P 8142

[0031] Printed gloss: The paper was printed on using an offset web press(four-color) by Toshiba Machine and special offset printing ink (LeoEcoo M by Toyo Ink), with the press operating at a speed of 600 rpm. Thesurface (solid areas of black, blue and red) of the printed paper wasthen measured in accordance with JIS P 8142.

[0032] Ink-impression property: The paper was printed on using an offsetweb press (four-color) by Toshiba Machine and special offset printingink (Leo Ecoo M by Toyo Ink), with the press operating at a speed of 600rpm. Ink-impression property was then visually evaluated over fourlevels on the surface (solid area of blue) of the printed paper. Theevaluation criteria used were: Excellent (), Good (◯), Poor (Δ) andUnacceptable (X).

[0033] Opacity: Measured in accordance with JIS P 8138

[0034] Density: Measured in accordance with JIS P 8118

[0035] Tensile strength: Measured using a tensile tester by Lorentzenand Wettre

[0036] Printing efficiency: Work efficiency (torn paper, etc.) duringoffset web printing was evaluated over four levels. The evaluationcriteria used were: Excellent (), Good (◯), Poor (Δ) and Unacceptable(X).

[Example 1]

[0037] A pigment mixture (volume distribution of particle sizes 0.40 μmto 4.20 μm: 66.6%) consisting of 80 parts of engineered kaoline(ECLIPS650 by Engelhard; volume distribution of particle sizes 0.40 μmto 4.20 μm: 65.3%) and 20 parts of fine-particle ground calciumcarbonate (FMT-90 by FIMATEC; volume distribution of particle sizes 0.40μm to 4.20 μm: 71.9%) was mixed with sodium polyacrylate added as adispersant to 0.2 part of the pigment, and the mixture was dispersed ina Cellier's mixer to prepare a pigment slurry with a solid content of70%. The pigment slurry thus obtained was mixed with four parts ofhollow plastic pigment with a diameter of 1.0 μm (HP1055 by Rohm andHaas), 10 parts of non-thickening type styrene-butadiene copolymer latex(glass transition point, 15° C.; gel content, 75%) and six parts ofhydroxyethyl etherified starch (PG295 by Penford), as well as water, toobtain a coating mixture with a solid content of 60%. The coatingmixture was applied to both sides of a wood-containing base paper with abasis weight of 30 g/m², wherein said base paper consisted of 30 wt-% ofmechanical pulp mixed with 4 wt-% of titanium dioxide and 4 wt-% of talcadded as fillers (all percentages relative to the weight of the basepaper), to a coating weight of 7 g/m² per side using a blade coateroperating at 800 m/min. The coated paper was then dried until themoisture content became 5.5%, after which it was processed viacalendering to obtain a coated paper with a tensile strength of 375kN/m.

[Example 2]

[0038] A coated paper was obtained in the same manner as described inExample 1, except that the pigment slurry with a solid content of 70%was obtained by dispersing in a Cellier's mixer a pigment mixture(volume distribution of particle sizes 0.40 μm to 4.20 μm: 68.7%)consisting of 70 parts of Brazilian kaoline (Capim DG by Rio Capim;volume distribution of particle sizes 0.40 μm to 4.20 μm: 68.4%) and 30parts of coarse-particle ground calcium carbonate (FMT-75 by FIMATEC;volume distribution of particle sizes 0.40 μm to 4.20 μm: 69.5%), towhich sodium polyacrylate was added as a dispersant to 0.2 part of thepigment.

[Example 3]

[0039] A coated paper was obtained in the same manner as described inExample 1, except that the coating mixture was applied to both sides ofa wood-containing base paper with a basis weight of 35 g/m², whereinsaid base paper consisted of 25 wt-% of mechanical pulp as well as 4wt-% of titanium dioxide and 4 wt-% of talc added as fillers (allpercentages relative to the weight of the base paper), to a coatingweight of 7 g/m² per side.

[Example 4]

[0040] A coated paper was obtained in the same manner as described inExample 1, except that the coating mixture was applied to both sides ofa wood-containing base paper with a basis weight of 35 g/m², whereinsaid base paper consisted of 10 wt-% of mechanical pulp as well as 3wt-% of titanium dioxide and 3 wt-% of talc added as fillers (allpercentages relative to the weight of the base paper), to a coatingweight of 7.5 g/m² per side, whereupon the tensile strength of theobtained coated paper was adjusted to 390 kN/m.

[Example 5]

[0041] A coated paper was obtained in the same manner as described inExample 1, except that the coating mixture was applied to both sides ofa wood-containing base paper with a basis weight of 35 g/m^(2,) whereinsaid base paper consisted of 25 wt-% of mechanical pulp as well as 6wt-% of titanium dioxide and 4 wt-% of talc added as fillers (allpercentages relative to the weight of the base paper), to a coatingweight of 6.5 g/m² per side, whereupon the tensile strength of theobtained coated paper was adjusted to 290 kN/m.

[Example 6]

[0042] A coated paper was obtained in the same manner as described inExample 1, except that the pigment slurry was prepared without theaddition of plastic pigment.

[Example 7]

[0043] A coated paper was obtained in the same manner as described inExample 1, except that the coating mixture was applied to both sides ofa wood-containing base paper with a basis weight of 30 g/m², whereinsaid base paper consisted of 30 wt-% of mechanical pulp and 4 wt-% oftalc added as a filler, to a coating weight of7 g/m² per side.

[Example 8]

[0044] A coated paper was obtained in the same manner as described inExample 1, except that the pigment slurry was prepared without theaddition of plastic pigment and the coating mixture was applied to bothsides of a wood-containing base paper with a basis weight of 30 g/m²,wherein said base paper consisted of 30 wt-% of mechanical pulp and 4wt-% of talc added as a filler, to a coating weight of7 g/m² per side.

[Example 9]

[0045] A coated paper was obtained in the same manner as described inExample 1, except that the pigment slurry was mixed with 4 parts ofhollow plastic pigment with a diameter of 1.0 μm, five parts of titaniumdioxide, 10 parts of non-thickening styrene-butadiene copolymer latex(glass transition point, 15° C.; gel content, 75%) and 6 parts ofhydroxyethyl etherified starch (PG295 by Penford), as well as water, toobtain a coating mixture with a solid content of 60%.

[Comparative Example 1]

[0046] A coated paper was obtained in the same manner as described inExample 1, except that a pigment mixture (volume distribution ofparticle sizes 0.40 μm to 4.20 μm: 62.5%) consisting of 80 parts of fineclay (MIRASHEEN by Engelhard; volume distribution of particle sizes 0.40μm to 4.20 μm: 60.2%) and 20 parts of fine-particle ground calciumcarbonate (FMT-90 by FIMATEC; volume distribution of particle sizes 0.40μm to 4.20 μm: 71.9%) was mixed with sodium polyacrylate added as adispersant to 0.2 part of the pigment, and the mixture was dispersed ina Cellier's mixer to prepare a pigment slurry with a solid content of70%.

[Comparative Example 2]

[0047] A coated paper was obtained in the same manner as described inExample 1, except that a pigment mixture (volume distribution ofparticle sizes 0.40 to 4.20 μm: 63.3%) consisting of 60 parts ofsecond-grade clay (DB KOTE by IMERYS; volume distribution of particlesizes 0.40 μm to 4.20 μm: 57.6%) and 40 parts of fine-particle groundcalcium carbonate (FMT-90 by FIMATEC; volume distribution of particlesizes 0.40 μm to 4.20 μm: 71.9%) was mixed with sodium polyacrylateadded as a dispersant to 0.2 part of the pigment, and the mixture wasdispersed in a Cellier's mixer to prepare a pigment slurry with a solidcontent of 70%.

[Comparative Example 3]

[0048] A coated paper was obtained in the same manner as described inExample 1, except that a pigment mixture (volume distribution ofparticle sizes 0.40 μm to 4.20 μm: 57.9%) consisting of 25 parts ofdelaminated clay (DB Plate by IMERYS; volume distribution of particlesizes 0.40 μm to 4.20 μm: 48.1%), 25 parts of #2 clay (DB KOTE byIMERYS; volume distribution of particle sizes 0.40 μm to 4.20 μm:57.6%), 25 parts of fine clay (AMAZON Plus by CADAM; volume distributionof particle sizes 0.40 μm to 4.20 μm: 53.8%) and 25 parts of fine groundcalcium carbonate (FMT-90 by FIMATEC; volume distribution of particlesizes 0.40 μm to 4.20 μm: 71.9%) was mixed with sodium polyacrylateadded as a dispersant to 0.2 part of the pigment, and the mixture wasdispersed in a Cellier's mixer to prepare a pigment slurry with a solidcontent of 70%.

[Comparative Example 4]

[0049] A coated paper was obtained in the same manner as described inExample 1, except that the coating mixture was applied to both sides ofa medium-grade paper with a basis weight of 32 g/m², wherein said basepaper consisted of 10 wt-% of mechanical pulp as well as 3 wt-% oftitanium dioxide and 4 wt-% of talc added as fillers (all percentagesrelative to the weight of the base paper), to a coating weight of 7 g/m²per side, whereupon the tensile strength of the obtained coated paperwas adjusted to 420 kN/m.

[0050] The results of the above examples are shown in Table 1. TABLE 1Volume distribution of particle sizes 0.40 Plastic pigment Titaniumdioxide Ink-impression μm to 4.20 μm, % content, part(s) content, wt-%Sheet gloss, % Printed gloss, % Opacity, % property Example 1 66.6 4 2.745.5 59.9 87.5 ⊚ Example 2 68.7 4 2.7 44.3 58.3 87.0 ⊚ Example 3 66.6 42.9 45.3 58.6 88.3 ⊚ Example 4 66.6 4 2.1 46.4 60.3 90.0 ⊚ Example 566.6 4 4.4 42.8 57.3 89.1 ◯ Example 6 66.6 0 2.7 43.2 57.8 86.9 ⊚Example 7 66.6 4 0 45.4 59.6 86.5 ⊚ Example 8 66.6 0 0 43.1 57.2 86.1 ⊚Example 9 66.6 4 4.0 45.2 59.0 89.2 ⊚ Comparative 62.5 4 2.7 47.1 54.387.2 ⊚ example 1 Comparative 63.3 4 2.7 40.3 53.2 87.7 ⊚ example 2Comparative 57.9 4 2.7 38.5 51.3 87.3 ⊚ example 3 Comparative 66.6 4 2.145.2 59.6 87.6 ⊚ example 4 Basis Tensile strength, Printability weight,g/m² Density, g/cm³ kN/m (torn paper) Example 1 44 1.02 375 ◯ Example 244 1.03 375 ◯ Example 3 49 1.01 375 ◯ Example 4 50 1.05 390 ⊚ Example 548 1.02 290 ◯ Example 6 44 1.04 375 ◯ Example 7 44 1.05 375 ◯ Example 844 1.04 375 ◯ Example 9 44 1.03 375 ◯ Comparative 44 1.05 375 ◯ example1 Comparative 44 1.03 375 ◯ example 2 Comparative 44 1.02 375 ◯ example3 Comparative 46 1.05 420 X example 4

[0051] The present invention allows for the production of a coated paperfor printing that is light in weight yet offers opacity suitable foractual use, possessing a relatively good ink-impression property andhigh printed gloss, and particularly an excellent printability thatprevents the paper from tearing during offset web printing.

What is claimed is:
 1. A coated paper for printing which comprises abase paper and a coating layer containing a pigment and an adhesive,wherein said coating layer has a volume distribution of 65% or more ofpigment particles ranging from 0.4 μm to 4.2 μm in size, and whereinsaid coated paper has a basis weight of 50 g/m² or less and tensilestrength ranging from 200 kN/m to 400 kN/m.
 2. The coated paper forprinting as described in claim 1, wherein said paper contains from 1 to20 weight-parts of hollow plastic pigment with a diameter of 0.8 μm ormore relative to 100 weight-parts of pigment.
 3. The coated paper forprinting as described in claim 1, further comprising 0.5 to 12 wt-% oftitanium dioxide relative to the weight of said paper.
 4. The coatedpaper for printing as described in claim 2, further comprising 0.5 to 12wt-% of titanium dioxide relative to the weight of said paper.